The information on mica capacitor current ratings came from a guy
called "Lenk" in Oceanside, California, At the time of the caveat
from Lenk, I was shopping for RF padder caps. As I recall, Lenk's
last name was Lenkert. He and an older mostly-retired fellow owned
an electronic emporium that specialized in surplus transmitting
components. A small part of the store was devoted to a mini-museum
of early transmitting apparatus. As I recall, in a glass display
case, he had an airborne spark transceiver from WW-I.
On Jul 13, 2006, at 4:13 AM, Tom W8JI wrote:
> So we are told that some manufacturers derate some mica
> caps above 5MHz. Others have caps that in slightly different
> applications have ratings that are high. Some mica caps can
> handle high currents in the VHF range. Dissipation factor
> wouldn't, prima facie. seem to be the critical parameter
> between all these products.
Dissipation factor is related to dielectric heating, and internal
heat is seemingly a factor in capacitor life.
>> I can't say that I'm any the wiser - possibly a little
>> better informed.
>> 73
>> Peter G3RZP
>
> Here's something I noticed about technical questions or
> topics. If someone gives a simple authoritative answer that
> everyone can just accept on the surface without having to
> understand the actual problem, it gets accepted.
I did not accept what Lenk told me unquestioningly. Instead, I went
home and dug through a junk box of WW-II surplus mica transmitting
caps. When I saw that current rating decreased as frequency
increased, I concluded that Lenk knew what he was talking about.
> That seems
> to be true even when the answer is so grossly oversimplified
> it winds up being wrong in the big picture.
>
> I think it is rooted in wanted an answer without learning
> how something really works.
I agree, Tom.
>
> 73 Tom
>
>
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R L MEASURES, AG6K. 805-386-3734
r@somis.org
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